Can a person be born a killer? That's the big mystery surrounding the massacre in Newtown - what caused Adam Lanza to murder his mother, then 26 others at Sandy Hook Elementary School.
Connecticut's chief medical examiner Dr. H. Wayne Carver has asked a geneticist to join in the investigation.
"I'm exploring with the department of genetics what might be possible, if anything is possible. Is there any identifiable disease associated with this behavior?" says Carver.
Is this a case of nature versus nurture?
OutFront tonight: Dr. Drew Pinsky – host of "Dr.Drew" on HLN and a practicing physician and psychiatrist.